Why is post_load called after schema.validate()?

Hello,

I noticed that @post_load is called when calling schema_object.validate().

Then I went to the library code and saw this (everything seemed OK, because I was getting a feeling postprocessing will not take a place):


It was obvious I will need some debugging, so I went through the calling stacktrace and got surprised when I saw the `marshalling` module calls the `deserialize` method which calls `schema_object.load()`. I don't think it is expected to have `post_load` called when you call `schema_object.validate()`, because in my case, we are performing some intensive operations, e.g. b64 decoding some string data and it takes some time. In this way, we have `post_load` called twice - the first time when a controller validates the input and the other when we actually load the data into a dict.

Of course, this is not a bug, but an open question.

Start by tracing the schema_object.validate() and schema_object.load() entry points through the marshalling module and its deserialize method. Determine whether post_load is intentionally invoked during validation, then document the expected lifecycle and whether the behavior should be avoided or changed.

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